Estimate your body fat for free!

There are lots of ways to estimate your body fat. Most involve hiring someone or buying expensive equipment.

This page describes two methods to estimate your body fat; both are free. The first method is described in The Essentials of Exercise Physiology. The second method is based on your weight and waist method, and was developed by the YMCA.

To estimate your body fat, you will need a tape measure to measure your girth. The measurement sites for method 1, depend on your age and sex; they are are listed in table 1 immediately below. Enter the appropriate values in table 2 which is further down. (Note: table 2 will list the correct sites after you enter your age and sex and then click somewhere on the page.)

Since it is impossible to measure yourself perfectly, I have estimated an error bound. I assume that at best, you can read a tape measure to within 1/4" of an inch and know your weight within 2 pounds. The uncertainty based on these errors is provided. So, you will read a result like:

body fat = 25% ± 2%.

That means your body fat % may fall between 23% and 27%; this range is due to the possibility of mismeasuring. The formula's generally claim that a standard error of 3%. These errors aren't necessarily additive. So, no matter what the formula claims, don't expect a true uncertainty of less than 3% There are additional uncertainties in the formula's themselves.

results:

I get different results with these two methods. I also have a body fat measuring scale at home, and a set of Accurate body fat calipers. The data I entered here are:

hip = 37 inches.
abdomen = 27 inches.
waist = 26.5 inches.
calf = 14 inches.
thigh 21.5 inches
age = 43
female.

My results are:

Method 1: 18.8% ± 0.3%
Method 2: (YMCA): 18% ± 1%
Fat Scale (at home): 21.3%
Fat Calipers (at home): 20%

These are all within 3% of each other, as claimed by the scale manufacturer, the fat caliper manufacturer and the people who created the formulas. Naturally, I have no idea which one is most accurate.

I use my fat scale to estimate my body fat. Why? Because I know I can't cheat by holding the tape really tight or lose!

Lucia

Where to measure.

Where to measure for Method 1: Find the row containing your age and sex. Read site A, B, and C. The exact location of the three regions is described below.

Table 1: Measurement Sites for Method 1
Age	Sex	Site A	Site B	Site C
18-26	M	Right upper arm	Abdomen	Right forearm
18-26	F	Abdomen	Right thigh	Right forearm
27-50	M	Buttocks	Abdomen	Right forearm
27-50	F	Abdomen	Right thigh	Right calf

Right upper arm: (biceps): Extend arm straight with palm facing up. Measure halfway between shoulder and elbow.
Right forearm: Extend arm straight with palm up. Measure the thickest point of the forearm.
Abdomen: Measure 1 inch above your belly button.
Buttocks: Stand with heels together. Measure at maximum protrusion of your butt.
Right Thigh: Stand up straight. Measure upper thigh just bellow buttocks.
Right calf: Stand up straight. Measure thickest part of calf.

Where to measure for Method 2: To use the YMCA method, weigh yourself and measure at the smallest location for your waist. If you don't have a smallest location, measure 1" above your belly button.

Enter Data to Estimate Body Fat Using Method 1
Enter then hit click.
Sex:	Male Female
Age:	years
Site 1()	inches
Site 2()	inches
Site 3()	inches
Individual contributions to calculation:	+++=
Percent body fat:	%± %
Click to

Enter Data to Estimate Body Fat Using Method 2 (The YMCA Method)
Sex:	Male Female
Weight:	lbs
Waist at smallest part.	inches
Individual contributions to calculation:	+++=
Percent body fat:	%± %
Click to

References

"Essentials of Exercise Physiology"

Hodgdon, J. and Beckett, M. Prediction of percent body fat for U.S. navy men and women from body circumferences and height. Reports No. 84-29 and 84-11. Naval Health Research Center, San Diego, Cal. 1984